The length characterizing the decrease with distance of the potential in the double layer = characteristic @D01533@ length in the corresponding electrolyte solution = \(\kappa^{-1}\):

\[\frac{1}{\kappa } = \sqrt{\frac{\varepsilon_{\text{r}}\varepsilon_{0}RT}{F^{2}\sum _{i}c_{i}z_{i}^{2} }}\]

(rationalized four-quantity system)

\[\frac{1}{\kappa } = \sqrt{\frac{\varepsilon_{\text{r}}RT}{4\pi F^{2}\sum _{i}c_{i}z_{i}^{2} }}\]

(three-quantity electrostatic system)

where \(\varepsilon\) = static @P04507@ = \(\varepsilon_{\text{r}}\varepsilon_{0}\), \(\varepsilon_{\text{r}}\) = relative static @P04507@ of solution; \(\varepsilon_{0}\) = @P04508@, \(R\) = @G02579@, \(T\) = @T06321@, \(F\) = @F02325@, \(z_{\text{i}}\) = concentration of species \(i\), \(z_{\text{i}}\) = ionic charge on species \(i\).